Raise an exception when event_type exceeds the max length (#48115)

* raise an exception when event_type exceeds the max length that the recorder supports

* add test

* use max length constant in recorder

* update config entry reloaded service name

* remove exception string function because it's not needed

* increase limit to 64 and revert event name change

* fix test

* assert exception args

* fix test

* add comment about migration

homeassistant/components/recorder/models.py

@@ -18,6 +18,7 @@ from sqlalchemy.ext.declarative import declarative_base
 from sqlalchemy.orm import relationship
 from sqlalchemy.orm.session import Session
 
+from homeassistant.const import MAX_LENGTH_EVENT_TYPE
 from homeassistant.core import Context, Event, EventOrigin, State, split_entity_id
 from homeassistant.helpers.json import JSONEncoder
 import homeassistant.util.dt as dt_util
@@ -53,7 +54,7 @@ class Events(Base):  # type: ignore
     }
     __tablename__ = TABLE_EVENTS
     event_id = Column(Integer, primary_key=True)
-    event_type = Column(String(64))
+    event_type = Column(String(MAX_LENGTH_EVENT_TYPE))
     event_data = Column(Text().with_variant(mysql.LONGTEXT, "mysql"))
     origin = Column(String(32))
     time_fired = Column(DATETIME_TYPE, index=True)

homeassistant/const.py

@@ -22,6 +22,10 @@ ENTITY_MATCH_ALL = "all"
 # If no name is specified
 DEVICE_DEFAULT_NAME = "Unnamed Device"
 
+# Max characters for an event_type (changing this requires a recorder
+# database migration)
+MAX_LENGTH_EVENT_TYPE = 64
+
 # Sun events
 SUN_EVENT_SUNSET = "sunset"
 SUN_EVENT_SUNRISE = "sunrise"

homeassistant/core.py

@@ -58,12 +58,14 @@ from homeassistant.const import (
     EVENT_TIMER_OUT_OF_SYNC,
     LENGTH_METERS,
     MATCH_ALL,
+    MAX_LENGTH_EVENT_TYPE,
     __version__,
 )
 from homeassistant.exceptions import (
     HomeAssistantError,
     InvalidEntityFormatError,
     InvalidStateError,
+    MaxLengthExceeded,
     ServiceNotFound,
     Unauthorized,
 )
@@ -697,6 +699,9 @@ class EventBus:
 
         This method must be run in the event loop.
         """
+        if len(event_type) > MAX_LENGTH_EVENT_TYPE:
+            raise MaxLengthExceeded(event_type, "event_type", MAX_LENGTH_EVENT_TYPE)
+
         listeners = self._listeners.get(event_type, [])
 
         # EVENT_HOMEASSISTANT_CLOSE should go only to his listeners

homeassistant/exceptions.py

@@ -154,3 +154,20 @@ class ServiceNotFound(HomeAssistantError):
     def __str__(self) -> str:
         """Return string representation."""
         return f"Unable to find service {self.domain}.{self.service}"
+
+
+class MaxLengthExceeded(HomeAssistantError):
+    """Raised when a property value has exceeded the max character length."""
+
+    def __init__(self, value: str, property_name: str, max_length: int) -> None:
+        """Initialize error."""
+        super().__init__(
+            self,
+            (
+                f"Value {value} for property {property_name} has a max length of "
+                f"{max_length} characters"
+            ),
+        )
+        self.value = value
+        self.property_name = property_name
+        self.max_length = max_length

tests/test_core.py

@@ -36,6 +36,7 @@ import homeassistant.core as ha
 from homeassistant.exceptions import (
     InvalidEntityFormatError,
     InvalidStateError,
+    MaxLengthExceeded,
     ServiceNotFound,
 )
 import homeassistant.util.dt as dt_util
@@ -524,6 +525,21 @@ async def test_eventbus_coroutine_event_listener(hass):
     assert len(coroutine_calls) == 1
 
 
+async def test_eventbus_max_length_exceeded(hass):
+    """Test that an exception is raised when the max character length is exceeded."""
+
+    long_evt_name = (
+        "this_event_exceeds_the_max_character_length_even_with_the_new_limit"
+    )
+
+    with pytest.raises(MaxLengthExceeded) as exc_info:
+        hass.bus.async_fire(long_evt_name)
+
+    assert exc_info.value.property_name == "event_type"
+    assert exc_info.value.max_length == 64
+    assert exc_info.value.value == long_evt_name
+
+
 def test_state_init():
     """Test state.init."""
     with pytest.raises(InvalidEntityFormatError):